Quote:
Originally Posted by PhilW
Also: thermal mass. There's too much material in the structure; the cells are not well ventilated; the mirrors are really thick.
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This becomes significant at larger sizes. I recall some months ago I was at MPAS with my 15"er with a number of other large dobs present.
At around midnight all scopes were turned to saturn and mine was the only scope out the lot giving a good image in what was good seeing.
The reason being that my cooling fan had been running all night working to keep my 1.6" thick mirror near ambient temp. The 16" lightbridge with its 2" thick mirror without fan going presented a boiling blob of an image.